Testimony began Thursday in the trial of a Utah plastic surgeon accused of murdering his wife by giving her a powerful cocktail of sedative drugs and drowning her in the bathtub.

Martin MacNeill, 57, is allegedly hounded his wife Michelle to get a facelift and then pressured her doctor to over-prescribe prescription painkillers. The doctor said he only agreed to the heavy prescription because MacNeill was a physician as well, the Salt Lake Tribunereports.

Prosecutors say MacNeill murdered his wife, who was found dead in the bathtub in 2007 by the couple’s then six-year-old daughter, in order to carry on with an extramarital affair. They say MacNeill exhibited strange behavior throughout his wife’s ordeal, including being unusually happy at his wife’s funeral and chatting about “how odd it was to be a bachelor again,” HLN reports. Prosecutors say jail inmates to whom MacNeill confessed his crimes will testify as well.

MacNeill’s defense team accuses investigators of being so eager to pin the woman’s death on MacNeill that they ignored forensic evidence. The original medical examination found that Michelle died of heart disease. The case was only reopened a year-and-a-half later at the request of family members, and a second examination found the woman died of a combination of heart disease and “drug toxicity.”